HOG'S FAT 421 The physical and chemical characters of oleomargarine are : Specific gravity at 15° ,, 98-100° Melting point .... ,, ,, of fatty acids Solidifying point of fatty acids. Zeiss refractometric reading, at 35° . 40° Acid number, if fresh and well stored Saponification number Iodine number. . . . . Fixed acid number .... Volatile ,, ,,.... . 0-924-0-930 0-859-0-863 32-35° (sometimes up to 40°) . 40-43° .. 39-42° 47-49 o 192-200 (195-198) 42-55 (43-48) 95-96 . o -4-1 -o Under the polarising microscope it behaves like fused butter (see 3 in article on Butter, Vol. II, Chapter II). HOG'S FAT Hog's fat is, strictly speaking, the fat of the inside of the animal, that adhering to the inside of the skin constituting lard. American hog's fat is divided into various qualities according to the method of preparation. In general the fat is white and pasty, with a peculiar odour and a sweetish taste ; it becomes rancid easily, turning yellow. It is only slightly soluble in alcohol. With the ordinary reagents for oils it gives no colour reactions. Its characters are given in Table XLVII. Detection of Adulterations.Lard is adulterated with or ^even replaced by mixtures of tallow, pressed tallow (also hardened or hydrogenised oils), cottonseed stearine or other vegetable fats, or cottonseed, sesame, arachis, maize, sunflower-seed, coco-nut or lard oil; also with pressed lard and vegetable oils. The artificial mixtures constituting lard substitutes often contain a small proportion of lard, recognisable mainly by its characteristic odour. Lards containing marked amounts of water, incorporated with the help of a little alkali, are also found. The various adulterations are detected as follows : 1. WATER, ALKALI AND OTHER MINERAL SUBSTANCES. The water is determined by drying the fat at 100° to constant weight. Alkalis and other mineral matters may be found by incinerating the fat and examining the ash ; the former may also be detected by treating with hot water and testing with litmus paper, or by passing a current of steam for half an hour into a mixture of 60 grams of the fat with 60 grams of water, then allowing the mass to cool and filtering : in presence of an alkali or an alkaline earth, a milky filtrate is obtained. 2. TALLOW, PRESSED TALLOW OR OTHER ANIMAL FAT OR HARDENED (HYDROGENISED) OIL. These substances are tested for by Earner's method,'1 1 Zeitschr. Unt. Nahr. Genussmittel, 1913, XXVI, p. 559- See also papers on this method by Bomer, Alpers, Fischer and Werwerinke, and Sprinkmeyer and Diedrichs (ibid., 1914, XXVII, pp. 142, 153, 361, 571).ermometer noierl.